MEDICAL, HEALTH AND SOCIAL ASPECTS OF HIVAIDS DIAGNOSIS SAYAD B' MD' MPH

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Detection of HIV infection In Medical, health
and social aspects of HIV/AIDS
Sayad B. M.D, MPH 2003
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HIV structure

• 1-Core
• Genome,Pr.,Enz.
• 2-envelope
• Host C.M. ,Pr

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HIV genom

• 1-env
• gp41,gp120,gp160
• 2-gag
• p7,p9,p17,p24
• 3-pol
• p11, p66,p32,p51

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HIV typing

• HIV1
• Group M (Include eight subgroup or cladA,B,C,)
• Group O
• Group N

• HIV2

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HIV life cycle

• Replication products
• Structural Pr.
• HIV RNA
• Proviral DNA

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HIV infection trend

• Direct assays in first 2-8 W.
• Serologic assays after 8W.

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Laboratory assays for HIV detection

• 1.Serologic assays
• 2.Direct assays

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Serologic assays

• Advantages
• Disadvantages
• Kinds of serologic assay
• 1-ELISA
• 2-Western blot

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ELISA

• Methodology
• Sensitivity 99
• Specificity 99

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Causes of false negative ELISA for HIV infection

• Primary HIV infection
• Immunosuppressed patient
• Errors in specimen labeling or handling
• HIV2 infection

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Causes of false positive ELISA for HIV infection

• Human error
• Hemodialysis
• Reactive rapid plasma reagin test
• Autoimmune disorders
• Multiple myeloma
• Hemophilia
• Alcoholic hepatitis
• Rabies vaccination
• Influenza vaccination
• Viral infections

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Western blot

• Methodology
• Sensitivity gt 90
• Spesificity gt99

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Causes of false negative western Blot for HIV
infection

• 20 of HIV2 positive sera
• 10 of HIV1 group O sera

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Causes of false positive western Blot for HIV
infection

• -Hyperbilirubinemia
• -Connective tissue disorders
• -Polyclonal gammopathies

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Answer the questions

• 1.Who is HIV-positive?
• 2-Why do we repeat ELISA?
• 3.Why do we perform W.B after positive double
  ELISA?

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Predictive value
PPVa/ab
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What do you do in the following conditions

• 1.First ELISA(HIV1/HIV2) is negative?
• 2.First ELISA(HIV1/HIV2) is positive and the
  second is negative?
• 3.Double ELISA(HIV1/HIV2) is positive and W.B is
  negative?
• 4.Double ELISA(HIV1/HIV2) is positive and W.B is
  indeterminate?

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Direct assays

• Advantages
• Disadvantages
• Kinds of direct assays
• P24 Ag detection
• Proviral DNA detection
• HIV-RNA DETECTION
• HIV-culture

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P24 Ag detection

• Methodology
• Sensitivity
• Acute inf 50-75
• Asymptomatic 4
• AIDS 70
• Specificity gt90

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Proviral DNA detection

• Methodology
• Sensitivity 95
• Specificity 98

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HIV-RNA detection

• Methodology
• Sensitivity gt95
• Specificity gt90

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HIV culture

• Methodology
• Sensitivity per case
• Specificity 100